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Timothy P Devarenne - One of the best experts on this subject based on the ideXlab platform.
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raman spectra and dft calculations for Tetraterpene hydrocarbons from the l race of the green microalga botryococcus braunii
Journal of Molecular Structure, 2017Co-Authors: Hye Jin Chun, Hem R Thapa, Sergio Waqued, Arum Han, Vladislav V Yakovlev, Jaan Laane, Timothy P DevarenneAbstract:Abstract The green microalga Botryococcus braunii produces large amounts of liquid hydrocarbons that can be used as a renewable source for producing transportation fuels. In the L race of B. braunii the Tetraterpene known as lycopadiene accumulates as the main hydrocarbon. Lycopadiene biosynthesis begins with the production of the eight carbon-carbon double bond (C=C) containing molecule lycopaoctaene, which is reduced to lycopadiene through four intermediates containing less C=C bonds. While the biosynthetic pathway for these hydrocarbons has recently been deciphered, a spectroscopic understanding of the molecular structure for these molecules remains to be reported. Here we describe the vibrational frequency assignments for all six L race hydrocarbons using density functional theory (DFT) calculations, showing that these molecules have between 312 and 348 vibrational frequencies. Experimental Raman spectroscopy analysis shows the regions for ν(C=C) stretch and CH2/CH3 bending vibrations offer unique spectral signatures allowing for the differentiation of several of the hydrocarbons from each other.
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Tetraterpene Synthase Substrate and Product Specificity in the Green Microalga Botryococcus braunii Race L
2017Co-Authors: Hem R Thapa, Su Tang, James C. Sacchettini, Timothy P DevarenneAbstract:Recently, the biosynthetic pathway for lycopadiene, a C40 tetraterpenoid hydrocarbon, was deciphered from the L race of Botryococcus braunii, an alga that produces hydrocarbon oils capable of being converted into combustible fuels. The lycopadiene pathway is initiated by the squalene synthase (SS)-like enzyme lycopaoctaene synthase (LOS), which catalyzes the head-to-head condensation of two C20 geranylgeranyl diphosphate (GGPP) molecules to produce C40 lycopaoctaene. LOS shows unusual substrate promiscuity for SS or SS-like enzymes by utilizing C15 farnesyl diphosphate (FPP) and C20 phytyl diphosphate in addition to GGPP as substrates. These three substrates can be combined by LOS individually or in combinations to produce six different hydrocarbons of C30, C35, and C40 chain lengths. To understand LOS substrate and product specificity, rational mutagenesis experiments were conducted based on sequence alignment with several SS proteins as well as a structural comparison with the human SS (HSS) crystal structure. Characterization of the LOS mutants in vitro identified Ser276 and Ala288 in the LOS active site as key amino acids responsible for controlling substrate binding, and thus the promiscuity of this enzyme. Mutating these residues to those found in HSS largely converted LOS from lycopaoctaene production to C30 squalene production. Furthermore, these studies were confirmed in vivo by expressing LOS in E. coli cells metabolically engineered to produce high FPP and GGPP levels. These studies also offer insights into Tetraterpene hydrocarbon metabolism in B. braunii and provide a foundation for engineering LOS for robust production of specific hydrocarbons of a desired chain length
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phylogenetic placement genome size and gc content of the liquid hydrocarbon producing green microalga botryococcus braunii strain berkeley showa chlorophyta
Journal of Phycology, 2010Co-Authors: Taylor L Weiss, Spencer J Johnston, Kazuhiro Fujisawa, Koremitsu Sumimoto, Shigeru Okada, Joseph Chappell, Timothy P DevarenneAbstract:We report the genome size and the GC content,and perform a phylogenetic analysis on Botryococcusbraunii Ku¨tz., a green, colony-forming, hydrocarbon-rich alga that is an attractive source for biopetro-leum. While the chemistry of the hydrocarbonsproduced by the B race of B. braunii has beenstudied for many years, there is a deficiency of infor-mation concerning the molecular biology of thisalga. In addition, there has been some discrepancyas to the phylogenetic placement of the Berkeley (orShowa) strain of the B race. To clarify its classifica-tion, we isolated the Berkeley strain nuclear SSU(18S) rRNA gene and b-actin cDNA and used thesesequences for phylogenetic analysis to determinethat the Berkeley strain belongs to the Trebouxio-phyceae class. This finding is in agreement withother B races of B. braunii, indicating the Berkeleystrain is a true B race of B. braunii. To better under-stand molecular aspects of B. braunii, we obtainedthe Berkeley strain genome size as a first step ingenome sequencing. Using flow cytometry, we deter-mined the B. braunii Berkeley genome size to be166.2 ± 2.2 Mb. We also estimated the GC contentof the Berkeley strain as 54.4 ± 1.2% for expressedgene sequences.Key index words:18S rRNA sequences;Botryococcusbraunii;Chlorophyta;GCcontent;genomesize;hydrocarbons; phylogenetic analysis; Trebouxio-phyceaeAbbreviations: 18S rRNA, nuclear SSU(18S)ribosomalRNA; cDNA, complementary DNA; RT–PCR,reverse transcription–PCRB. braunii is a green, colonial microalga withunique liquid-hydrocarbon biosynthetic capabilitiesthat have made this organism a promising source ofrenewable hydrocarbon fuels. The cells of a B. brau-nii colony are held together by an extracellularmatrix composed of a polymer core of aldehydesderived from very long-chain fatty acids (Maxwellet al. 1968, Knights et al. 1970). Although some B.braunii liquid hydrocarbons can be found intracellu-larly, most liquid hydrocarbons are retained withinthe colony extracellular matrix.Three distinct races of B. braunii (A, B, and L)are classified by the type of hydrocarbons occurringin the extracellular matrix. The A race accumulatesthe fatty acid–derived alkadienes and alkatrienes,while the L race accumulates the Tetraterpene lyco-padiene. The focus of this study, the B race, accu-mulates the triterpenoid hydrocarbons known asbotryococcenes (Banerjee et al. 2002, Metzger andLargeau 2005).B. braunii possesses many characteristics thatmake it attractive as a biofuel feedstock source.B. braunii has been observed forming massive, densefreshwater blooms, and it is suggested that B. brau-nii oils have contributed to oil deposits throughoutthe world (Traverse 1955, Gelpi et al. 1968, Wake
Shigeru Okada - One of the best experts on this subject based on the ideXlab platform.
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effects of 2 azahypoxanthine on extracellular terpene accumulations by the green microalga botryococcus braunii race b
Algal Research-Biomass Biofuels and Bioproducts, 2016Co-Authors: Hiromasa Nakamura, Shigeki Matsunaga, Hirokazu Kawagishi, Shigeru OkadaAbstract:Abstract The B race of the green microalga Botryococcus braunii accumulates large amounts of triterpene hydrocarbons that are attractive as a source for biofuels. The alga, however, exhibits rather slow growth and this characteristic has hindered its practical application for biofuel production. In order to test a phytohormone-like compound that may regulate the growth or hydrocarbon production of this alga, the effects of 2-azahypoxanthine (AHX) on algal biomass and terpene contents in the extracellular matrix (ECM) in the Showa strain of B. braunii were investigated. The biomass of the Showa strain increased with AHX supplementation under static culture conditions although such effects were not observed in cultures with aeration or agitation. AHX supplementation significantly induced the accumulation of secondary carotenoids, including species-specific tetramethylsqualene (TMS)-conjugated carotenoids, botryoxanthin A and braunixanthin 1. Conversely, the addition of AHX showed a tendency to slightly lower the triterpene hydrocarbon (botryococcenes) content in the ECM. These metabolic changes in tri- and Tetraterpene accumulation could be caused by a reduction in nitrogen uptake from the culture medium due to AHX addition. Thus, there is a possibility that AHX could be used as a reagent to modulate terpene biosynthesis in the B race of B. braunii .
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phylogenetic placement genome size and gc content of the liquid hydrocarbon producing green microalga botryococcus braunii strain berkeley showa chlorophyta
Journal of Phycology, 2010Co-Authors: Taylor L Weiss, Spencer J Johnston, Kazuhiro Fujisawa, Koremitsu Sumimoto, Shigeru Okada, Joseph Chappell, Timothy P DevarenneAbstract:We report the genome size and the GC content,and perform a phylogenetic analysis on Botryococcusbraunii Ku¨tz., a green, colony-forming, hydrocarbon-rich alga that is an attractive source for biopetro-leum. While the chemistry of the hydrocarbonsproduced by the B race of B. braunii has beenstudied for many years, there is a deficiency of infor-mation concerning the molecular biology of thisalga. In addition, there has been some discrepancyas to the phylogenetic placement of the Berkeley (orShowa) strain of the B race. To clarify its classifica-tion, we isolated the Berkeley strain nuclear SSU(18S) rRNA gene and b-actin cDNA and used thesesequences for phylogenetic analysis to determinethat the Berkeley strain belongs to the Trebouxio-phyceae class. This finding is in agreement withother B races of B. braunii, indicating the Berkeleystrain is a true B race of B. braunii. To better under-stand molecular aspects of B. braunii, we obtainedthe Berkeley strain genome size as a first step ingenome sequencing. Using flow cytometry, we deter-mined the B. braunii Berkeley genome size to be166.2 ± 2.2 Mb. We also estimated the GC contentof the Berkeley strain as 54.4 ± 1.2% for expressedgene sequences.Key index words:18S rRNA sequences;Botryococcusbraunii;Chlorophyta;GCcontent;genomesize;hydrocarbons; phylogenetic analysis; Trebouxio-phyceaeAbbreviations: 18S rRNA, nuclear SSU(18S)ribosomalRNA; cDNA, complementary DNA; RT–PCR,reverse transcription–PCRB. braunii is a green, colonial microalga withunique liquid-hydrocarbon biosynthetic capabilitiesthat have made this organism a promising source ofrenewable hydrocarbon fuels. The cells of a B. brau-nii colony are held together by an extracellularmatrix composed of a polymer core of aldehydesderived from very long-chain fatty acids (Maxwellet al. 1968, Knights et al. 1970). Although some B.braunii liquid hydrocarbons can be found intracellu-larly, most liquid hydrocarbons are retained withinthe colony extracellular matrix.Three distinct races of B. braunii (A, B, and L)are classified by the type of hydrocarbons occurringin the extracellular matrix. The A race accumulatesthe fatty acid–derived alkadienes and alkatrienes,while the L race accumulates the Tetraterpene lyco-padiene. The focus of this study, the B race, accu-mulates the triterpenoid hydrocarbons known asbotryococcenes (Banerjee et al. 2002, Metzger andLargeau 2005).B. braunii possesses many characteristics thatmake it attractive as a biofuel feedstock source.B. braunii has been observed forming massive, densefreshwater blooms, and it is suggested that B. brau-nii oils have contributed to oil deposits throughoutthe world (Traverse 1955, Gelpi et al. 1968, Wake
James C. Sacchettini - One of the best experts on this subject based on the ideXlab platform.
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Tetraterpene Synthase Substrate and Product Specificity in the Green Microalga Botryococcus braunii Race L
ACS chemical biology, 2017Co-Authors: Hem R Thapa, Su Tang, James C. SacchettiniAbstract:Recently, the biosynthetic pathway for lycopadiene, a C40 tetraterpenoid hydrocarbon, was deciphered from the L race of Botryococcus braunii, an alga that produces hydrocarbon oils capable of being converted into combustible fuels. The lycopadiene pathway is initiated by the squalene synthase (SS)-like enzyme lycopaoctaene synthase (LOS), which catalyzes the head-to-head condensation of two C20 geranylgeranyl diphosphate (GGPP) molecules to produce C40 lycopaoctaene. LOS shows unusual substrate promiscuity for SS or SS-like enzymes by utilizing C15 farnesyl diphosphate (FPP) and C20 phytyl diphosphate in addition to GGPP as substrates. These three substrates can be combined by LOS individually or in combinations to produce six different hydrocarbons of C30, C35, and C40 chain lengths. To understand LOS substrate and product specificity, rational mutagenesis experiments were conducted based on sequence alignment with several SS proteins as well as a structural comparison with the human SS (HSS) crystal str...
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Tetraterpene Synthase Substrate and Product Specificity in the Green Microalga Botryococcus braunii Race L
2017Co-Authors: Hem R Thapa, Su Tang, James C. Sacchettini, Timothy P DevarenneAbstract:Recently, the biosynthetic pathway for lycopadiene, a C40 tetraterpenoid hydrocarbon, was deciphered from the L race of Botryococcus braunii, an alga that produces hydrocarbon oils capable of being converted into combustible fuels. The lycopadiene pathway is initiated by the squalene synthase (SS)-like enzyme lycopaoctaene synthase (LOS), which catalyzes the head-to-head condensation of two C20 geranylgeranyl diphosphate (GGPP) molecules to produce C40 lycopaoctaene. LOS shows unusual substrate promiscuity for SS or SS-like enzymes by utilizing C15 farnesyl diphosphate (FPP) and C20 phytyl diphosphate in addition to GGPP as substrates. These three substrates can be combined by LOS individually or in combinations to produce six different hydrocarbons of C30, C35, and C40 chain lengths. To understand LOS substrate and product specificity, rational mutagenesis experiments were conducted based on sequence alignment with several SS proteins as well as a structural comparison with the human SS (HSS) crystal structure. Characterization of the LOS mutants in vitro identified Ser276 and Ala288 in the LOS active site as key amino acids responsible for controlling substrate binding, and thus the promiscuity of this enzyme. Mutating these residues to those found in HSS largely converted LOS from lycopaoctaene production to C30 squalene production. Furthermore, these studies were confirmed in vivo by expressing LOS in E. coli cells metabolically engineered to produce high FPP and GGPP levels. These studies also offer insights into Tetraterpene hydrocarbon metabolism in B. braunii and provide a foundation for engineering LOS for robust production of specific hydrocarbons of a desired chain length
Hem R Thapa - One of the best experts on this subject based on the ideXlab platform.
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Tetraterpene Synthase Substrate and Product Specificity in the Green Microalga Botryococcus braunii Race L
ACS chemical biology, 2017Co-Authors: Hem R Thapa, Su Tang, James C. SacchettiniAbstract:Recently, the biosynthetic pathway for lycopadiene, a C40 tetraterpenoid hydrocarbon, was deciphered from the L race of Botryococcus braunii, an alga that produces hydrocarbon oils capable of being converted into combustible fuels. The lycopadiene pathway is initiated by the squalene synthase (SS)-like enzyme lycopaoctaene synthase (LOS), which catalyzes the head-to-head condensation of two C20 geranylgeranyl diphosphate (GGPP) molecules to produce C40 lycopaoctaene. LOS shows unusual substrate promiscuity for SS or SS-like enzymes by utilizing C15 farnesyl diphosphate (FPP) and C20 phytyl diphosphate in addition to GGPP as substrates. These three substrates can be combined by LOS individually or in combinations to produce six different hydrocarbons of C30, C35, and C40 chain lengths. To understand LOS substrate and product specificity, rational mutagenesis experiments were conducted based on sequence alignment with several SS proteins as well as a structural comparison with the human SS (HSS) crystal str...
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raman spectra and dft calculations for Tetraterpene hydrocarbons from the l race of the green microalga botryococcus braunii
Journal of Molecular Structure, 2017Co-Authors: Hye Jin Chun, Hem R Thapa, Sergio Waqued, Arum Han, Vladislav V Yakovlev, Jaan Laane, Timothy P DevarenneAbstract:Abstract The green microalga Botryococcus braunii produces large amounts of liquid hydrocarbons that can be used as a renewable source for producing transportation fuels. In the L race of B. braunii the Tetraterpene known as lycopadiene accumulates as the main hydrocarbon. Lycopadiene biosynthesis begins with the production of the eight carbon-carbon double bond (C=C) containing molecule lycopaoctaene, which is reduced to lycopadiene through four intermediates containing less C=C bonds. While the biosynthetic pathway for these hydrocarbons has recently been deciphered, a spectroscopic understanding of the molecular structure for these molecules remains to be reported. Here we describe the vibrational frequency assignments for all six L race hydrocarbons using density functional theory (DFT) calculations, showing that these molecules have between 312 and 348 vibrational frequencies. Experimental Raman spectroscopy analysis shows the regions for ν(C=C) stretch and CH2/CH3 bending vibrations offer unique spectral signatures allowing for the differentiation of several of the hydrocarbons from each other.
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Tetraterpene Synthase Substrate and Product Specificity in the Green Microalga Botryococcus braunii Race L
2017Co-Authors: Hem R Thapa, Su Tang, James C. Sacchettini, Timothy P DevarenneAbstract:Recently, the biosynthetic pathway for lycopadiene, a C40 tetraterpenoid hydrocarbon, was deciphered from the L race of Botryococcus braunii, an alga that produces hydrocarbon oils capable of being converted into combustible fuels. The lycopadiene pathway is initiated by the squalene synthase (SS)-like enzyme lycopaoctaene synthase (LOS), which catalyzes the head-to-head condensation of two C20 geranylgeranyl diphosphate (GGPP) molecules to produce C40 lycopaoctaene. LOS shows unusual substrate promiscuity for SS or SS-like enzymes by utilizing C15 farnesyl diphosphate (FPP) and C20 phytyl diphosphate in addition to GGPP as substrates. These three substrates can be combined by LOS individually or in combinations to produce six different hydrocarbons of C30, C35, and C40 chain lengths. To understand LOS substrate and product specificity, rational mutagenesis experiments were conducted based on sequence alignment with several SS proteins as well as a structural comparison with the human SS (HSS) crystal structure. Characterization of the LOS mutants in vitro identified Ser276 and Ala288 in the LOS active site as key amino acids responsible for controlling substrate binding, and thus the promiscuity of this enzyme. Mutating these residues to those found in HSS largely converted LOS from lycopaoctaene production to C30 squalene production. Furthermore, these studies were confirmed in vivo by expressing LOS in E. coli cells metabolically engineered to produce high FPP and GGPP levels. These studies also offer insights into Tetraterpene hydrocarbon metabolism in B. braunii and provide a foundation for engineering LOS for robust production of specific hydrocarbons of a desired chain length
Mahmoud Zaki Elreadi - One of the best experts on this subject based on the ideXlab platform.
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secondary metabolites from plants inhibiting abc transporters and reversing resistance of cancer cells and microbes to cytotoxic and antimicrobial agents
Frontiers in Microbiology, 2012Co-Authors: Michael Wink, Mohamed L Ashour, Mahmoud Zaki ElreadiAbstract:Fungal, bacterial, and cancer cells can develop resistance against antifungal, antibacterial, or anticancer agents. Mechanisms of resistance are complex and often multifactorial. Mechanisms include: (1) Activation of ATP-binding cassette (ABC) transporters, such as P-gp, which pump out lipophilic compounds that have entered a cell, (2) Activation of cytochrome p450 oxidases which can oxidize lipophilic agents to make them more hydrophilic and accessible for conjugation reaction with glucuronic acid, sulfate, or amino acids, and (3) Activation of glutathione transferase, which can conjugate xenobiotics. This review summarizes the evidence that secondary metabolites (SM) of plants, such as alkaloids, phenolics, and terpenoids can interfere with ABC transporters in cancer cells, parasites, bacteria, and fungi. Among the active natural products several lipophilic terpenoids [monoterpenes, diterpenes, triterpenes (including saponins), steroids (including cardiac glycosides), and Tetraterpenes] but also some alkaloids (isoquinoline, protoberberine, quinoline, indole, monoterpene indole, and steroidal alkaloids) function probably as competitive inhibitors of P-gp, multiple resistance-associated protein 1, and Breast cancer resistance protein in cancer cells, or efflux pumps in bacteria (NorA) and fungi. More polar phenolics (phenolic acids, flavonoids, catechins, chalcones, xanthones, stilbenes, anthocyanins, tannins, anthraquinones, and naphthoquinones) directly inhibit proteins forming several hydrogen and ionic bonds and thus disturbing the 3D structure of the transporters. The natural products may be interesting in medicine or agriculture as they can enhance the activity of active chemotherapeutics or pesticides or even reverse multidrug resistance, at least partially, of adapted and resistant cells. If these SM are applied in combination with a cytotoxic or antimicrobial agent, they may reverse resistance in a synergistic fashion.